1. Field of the Invention
The invention relates to a smelting unit as set forth below.
Smelting units of the kind set forth in the classifying portion are generally operated as an arc furnace and for that purpose mostly have a plurality of bar electrodes which can be introduced through suitable openings in the vessel cover into the furnace vessel in order there to melt charge material in the furnace vessel, with the formation of an arc therein. It is necessary for the furnace to be tiled both for the operation of removing slag from the molten bath during the melting operation and also for tapping off the furnace vessel after the melting operation has been concluded.
The electrodes which are introduced into the furnace vessel through the electrode openings in the furnace vessel cover are to remain in the furnace vessel at least during the operation of removing slag. In that respect, it is necessary to ensure that the bar electrodes do not suffer from damage as a result of a relative movement between the vessel cover and the bar electrodes. In the case of furnace vessels which are arranged on a furnace rocking cradle for the purposes of producing the tilting movement, because of the large distance between the plane in which the bar electrodes pass through the vessel cover and the rolling plane on which the furnace rocking cradle performs its rolling movement, it is necessary for the bar electrodes to be entrained in the tilting movement of the furnace vessel.
2. Description of the Related Art
German laid-open application (DE-OS) No. 14 33 424 discloses a smelting unit having a furnace which can be tilted by means of a furnace rocking cradle and which is adapted to be heated by bar electrodes which are passed through the vessel cover of the furnace. The bar electrodes are connected to the electrode lift devices by way of support arms. The electrode lift devices are disposed on a cover support mechanism which is in the form of a pivot arm and which is connected to the vessel cover on the one hand and which on the other hand can be coupled to a lifting/pivoting mechanism for lifting and pivoting movement of the vessel cover relative to the furnace vessel. The pivot arm, the electrode lift devices and the bar electrodes which are connected to the electrode lift devices by way of the support arms, together with the vessel cover, form a cover unit. In operation of the arc furnace, the cover unit lies on the furnace vessel and is uncoupled from the lifting/pivoting mechanism. The bar electrodes which are introduced into the furnace vessel through the vessel cover can thus follow the tilting movements of the furnace without the possibility of a tilting movement occurring between them and the furnace cover.
However that known smelting unit suffers from the disadvantage that, during tilting of the furnace, the entire cover unit consisting of the cover support mechanism, the pivot arm, the electrode lift devices, the electrode support arms and the bar electrodes as well as the vessel cover must be moved if the vessel cover remains on the furnace vessel during the slag removal operation or tapping operation. The movement of that considerable mass makes it necessary to provide for a stable structure for the tilting mechanism as well as a tilting drive which is of a correspondingly powerful nature.